Decorative capped wheel nut and method of assembly

ABSTRACT

A decorative cap and wheel nut or bolt insert, and a method of assembling them. The insert is coated and/or plated and includes a hex-shaped section and a section having a circular cylindrical outer surface. A cap includes a hex cross-section segment and a circular cylindrical cross-section segment. The hex cross-section segment of the cap slips easily over the hex section of the insert while the circular cylindrical cross-section segment has a smaller ID than the OD of the circular cylindrical insert section whereby an interference fit is formed between them when the insert is press fit into the cap.

FIELD OF THE INVENTION

This invention relates generally to wheel nuts or bolts for securing a vehicle wheel, i.e., a tire and rim, on a motor vehicle. It relates particularly to a decorative capped wheel nut or bolt and a method of assembly.

BACKGROUND OF THE INVENTION

Decorative capped wheel nuts and bolts are well-known in the automotive art. A decorative capped wheel nut, for example, conventionally comprises a nut insert and a decorative cap which is fastened to the insert by welding, crimping or with an adhesive. Examples of these constructions are illustrated in various prior art patents, including the Toth U.S. Pat. No. 4,955,773, the Bydalek U.S. Pat. No. 5,772,377, the Chaivre U.S. Pat. Nos. 4,018,133, and 4,056,862, the Baltzell U.S. Pat. No. 4,764,070 and the Somers et al. U.S. Pat. No. 6,036,420, for example. It is also known to form threads in a cap and in a lug nut and thread the cap onto the nut. See the Nolan et al. U.S. Pat. No. 5,180,266 in this regard.

All methods described in the prior art require relatively complex structures, assembly procedures and/or additional components. Assemblies produced by welding require expensive and sophisticated equipment for practical implementation of production. Practical options for plating the inserts are limited where welding is employed, placing welded designs at a disadvantage for achieving high corrosion resistance. Crimped designs require the addition of components, i.e., a sealant or o-ring, which complicates automated assembly. The use of adhesives causes similar problems. Because of the nature of the welding processes, or the introduction of extra components, production rates for these assembly processes are low.

SUMMARY OF THE INVENTION

An object of the invention is to provide an improved decorative capped wheel nut or wheel bolt.

Another object is to provide a decorative capped wheel nut or wheel bolt wherein the decorative cap is secured to the nut or bolt insert without welding, applying an adhesive, or using a sealant or O-ring.

Yet another object is to provide a decorative cap and insert assembly which is simpler and less expensive, but just as reliable, as prior art assemblies.

Still another object is to provide a new and improved method of assembling a decorative cap and nut or bolt insert.

The foregoing and other objects are realized in an insert and cap assembly wherein the components are securely fastened together by creating an interference fit between the cap and the insert. Specifically, the insert includes at least one section with a plated, coated or plated and coated circular cylindrical outer surface. The cap has a corresponding segment with a circular cylindrical inner surface which has an inside diameter 0.010 to 0.030 inches smaller than the outside diameter of the coated circular cylindrical outer surface. The insert is press fit into the cap, driving the cap's cylindrical inner surface over the insert's coated circular cylindrical outer surface. A 0.002 to 0.006 inches interference fit is formed around the interfering circular cylindrical surfaces.

The improved method of retaining a cap on the insert body requires only two components, the cap and the insert, thus reducing the extra expense of an additional component and the complexities of introducing this extra component into the assembly process. It also allows the use of all types of coating, plating and coating or plating alone on the insert, which is not possible using current welding assembly methods. Further cost savings may be achieved with higher assembly rates using simple hydraulic, pneumatic, or mechanical press equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, including its construction and method of operation, is illustrated more or less diagrammatically in the drawings, in which:

FIG. 1 is a side elevational view of a first embodiment of the invention in a decorative capped wheel nut assembly;

FIG. 2 is a top plan view of the wheel nut assembly seen in FIG. 1;

FIG. 3 is a side elevational view of the nut insert for the decorative capped wheel nut assembly seen in FIGS. 1 and 2;

FIG. 4 is a top plan view of the nut insert seen in FIG. 3;

FIG. 5 is a bottom plan view of the cap for the decorative capped wheel nut assembly seen in FIGS. 1 and 2;

FIG. 6 is a sectional view taken along line 6—6 of FIG. 2;

FIG. 7 is a diagrammatic illustration of an insert being press fit into a cap in a mechanical press;

FIG. 8 is a side view, partially in elevation and partially in section, of a second embodiment of the capped invention;

FIG. 9 is a top plan view of the capped wheel nut assembly seen in FIG. 8;

FIG. 10 is a split elevational/sectional view, similar to FIG. 8, of a third embodiment of the capped wheel nut assembly invention;

FIG. 11 is a top plan view of the capped wheel nut assembly seen in FIG. 10;

FIG. 12 is a split elevational/sectional view, similar to FIG. 8, of a fourth embodiment of the invention, a decorative capped wheel bolt assembly;

FIG. 13 is a top plan view of the capped wheel bolt assembly seen in FIG. 12;

FIG. 14 is a split elevational/sectional view, similar to FIG. 8, of a fifth embodiment of the invention, another decorative capped wheel bolt assembly;

FIG. 15 is a top plan view of the capped wheel bolt assembly seen in FIG. 14;

FIG. 16 is a split elevational/sectional view, similar to FIG. 8, of a sixth embodiment of the invention, another capped wheel nut assembly; and

FIG. 17 is a top plan view of the capped wheel nut assembly seen in FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and particularly to FIGS. 1–6, a decorative capped wheel nut assembly comprising a first embodiment of the present invention is seen generally at 10. The wheel nut assembly 10 includes a nut insert 12 and a decorative cap 14 fastened securely together by a method embodying features of the invention.

FIGS. 1, 2 and 6 illustrate the wheel nut 10 assembly, i.e., an assembled nut insert 12 and cap 14. FIGS. 3 and 4 illustrate a nut insert 12 separately. FIG. 5 illustrates a cap 14 separately (end view).

As seen in FIGS. 3, 4 and 6, the nut insert 12 comprises a body 21 having a cylindrical bore 23 extending axially through it from a hex-shaped section 24 on one end to a frusto-conical base 25 on the other. The nut insert 12 is commonly referred to as a hex-nut insert and is fabricated in a conventional manner of carbon steel. The frusto-conical base 25 is adapted to seat in a conventional manner in a wheel rim aperture (not shown) to fasten the wheel rim to a vehicle wheel stud (not shown). The bore 23 is internally threaded at its inner end 27 to receive the stud.

The nut insert 12 is coated in a conventional manner to prevent oxidation of exposed areas. In the embodiment illustrated a coating of GEOMET brand coating material available from Metal Coatings International, Inc. of Chardon, Ohio, is applied. GEOMET is a coating comprised mainly of overlapping zinc and aluminum flake in an inorganic binder, and is chromium free. It is applied over the entire insert 12 to a thickness of 0.001 inches.

Between the hex-shaped section 24 and the frusto-conical base 25, the insert body 21 has two cylindrical body sections 31 and 33. The section 31 of the illustrated insert body 21 has a cylindrical outer (coated) surface 35 with an outside diameter (OD) of 0.930 inches. The surface 35 has an axial length of 0.130 inches. The section 33 has a cylindrical outer (coated) surface 39 with an OD of 0.955 inches. The surface 33 has an axial length of 0.0625 inches. A radially extending shoulder 41 is formed between the two cylindrical surfaces 31 and 33.

As seen in FIGS. 2, 5 and 6, the cap 14 comprises three axially aligned wall segments; a dome-shaped end wall segment 51, a hex cross-section side wall segment 53 and a circular cylindrical side wall segment 55. The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment 53 are such that it slips easily over the coated, hex-shaped section 24 of the insert body. According to the invention, however, as will hereinafter be further discussed, the internal cross-sectional dimension of the circular cylindrical side wall segment 55 is such that a predetermined interference fit is formed between the inner surface 57 of the wall segment 55 and the coated cylindrical outer surface 35 of the insert body 21 when the cap 14 is press fit onto the insert 12.

The cap 14 is fabricated of stainless steel sheet with a nominal thickness of 0.018 to 0.020 inches. The inside diameter (ID) of the cylindrical wall segment 55 is preferably 0.910 inches. When the cap 14 is pressed onto the insert 12, the cylindrical wall segment 55 undergoes both plastic and elastic deformation. The portion of deformation that is plastic serves to allow a reasonable manufacturing tolerance for both components. The elastic deformation results in tensile hoop stresses in the cap 14 and constitutes the mechanism by which the cap 14 is retained on the insert 12. The resulting interference fit is approximately 0.0025, varying with changes in cap wall thickness or mechanical properties of the cap material.

FIG. 7 illustrates the assembly of a nut insert 12 into a cap 14 in a simple mechanical press P. The press P comprises a fixed die D1 in which the cap 14 is seated. A movable die D2 receives the insert 12 and drives it downwardly onto the cap 14 under the influence of pressure exerted in a conventional manner by the mechanical press P. The fixed die D1 receives the cap 14 is a well W. The well W is dimensioned to permit the radial expansion of the cylindrical side wall segment 55 which takes place in the cap 14 as the insert 12 is press fit into the cap 14.

Referring now to FIGS. 8 and 9, a decorative capped wheel nut assembly comprising a second embodiment of the invention is seen generally at 110. The assembly 110 includes a nut insert 112 and a decorative cap 114 fastened together according to the present invention.

The nut insert 112 comprises a body 121 having a cylindrical bore 123 extending axially through it from a cylindrical section 131 on one end to a frusto-conical base 125 on the other. The base 125 is adapted to seat in a wheel rim aperture (not shown). The bore 123 is internally threaded at 127. The insert 112 is coated in a manner previously discussed.

Between the conical base 125 and the cylindrical section 131, there is a hex-shaped section 124. The hex-shaped section 124 corresponds to the hex section 24 in the insert body 21 of the assembly 10.

The axially outer, or end cylindrical section 131, has a coated cylindrical outer surface 135 with an OD of 0.660 inches. The surface 135 has an axial length of 0.190 inches.

As seen in FIG. 8 the cap 114, which is again formed from stainless steel sheet, comprises four axially aligned segments; a dome shaped end wall segment 151, a cylindrical side wall segment 155, a hex-shaped side wall segment 153 and a frusto-conical lip 152. The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment 153 are such that it slips easily over the coated hex-shaped section 124 in the insert body 121.

The ID of the cylindrical wall segment 155 is 0.640 inches. When the cap 114 is pressed onto the insert 112, the cylindrical wall segment 155 undergoes both plastic and elastic deformation in the manner hereinbefore discussed with relation to the cap 14. The elastic deformation constitutes the mechanism by which the cap 114 is retained on the insert 112. The resulting interference fit is approximately 0.0025, again varying with changes in cap wall thickness or mechanical properties of the cap material.

Referring now to FIGS. 10 and 11, a decorative capped wheel nut assembly comprising a third embodiment of the invention is seen generally at 210. The assembly 210 includes a nut insert 212 and a decorative cap 214 fastened together according to the invention.

The nut insert 212 comprises a body 221 having a cylindrical bore 223 extending axially through it from a cylindrical section 231 on one end to a frusto-conical base 225 on the other. The base 225 is adapted to seat in a wheel rim aperture (not shown). The bore 223 is internally threaded at 227. Like the inserts 12 and 112, the insert 212 is coated.

Between the conical base 225 and the cylindrical section 231 there is a hex-shaped section 224. The hex-shaped section 224 corresponds to the section 24 in the insert body 21 of the insert 24.

Between the hex-shaped section 224 and the frusto-conical base 225, the insert body 221 has two cylindrical body sections 233 and 234. The axially outer cylindrical section 233 of the illustrated insert body 221 has a coated cylindrical outer surface 235 with an outside diameter (OD) of 0.930 inches. The surface 235 has an axial length of 0.130 inches. A radially extending shoulder 241 is formed between the two cylindrical surfaces 233 and 234.

The end cylindrical section 231 has a coated cylindrical outer surface 236 with an OD of 0.660 inches. The surface 236 has an axial length of 0.190 inches.

As seen in FIG. 11, the cap 214, again formed of stainless steel sheet, comprises four axially aligned segments; a dome shaped end wall segment 251, an end circular cylindrical side wall segment 255, a hex-shaped side wall segment 253 and a circular cylindrical side wall segment 252. The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment 253 are such that it will slip freely over the coated hex-shaped section 224 in the insert body 221.

The ID of the cylindrical wall segment 255 is 0.640 inches. When the cap 214 is pressed onto the insert 212, the cylindrical wall segment 255 undergoes the aforedescribed plastic and elastic deformation as it is forced over the coated cylindrical surface 236. The resulting interference fit is again approximately 0.0025.

The ID of the cylindrical wall segment 252 is 0.910 inches. As such, an interference fit of 0.0025 inches is effected at the same time between the wall segment 252 and the coated outer surface 235 of the end cylindrical section 231.

In FIGS. 12–15 the invention is seen in the context of a wheel bolt rather than a wheel nut. Referring specifically to FIGS. 12 and 13, a decorative capped wheel bolt assembly comprising a fourth embodiment of the invention is seen generally at 310. The assembly 310 includes a bolt insert 312 and a decorative cap 314.

The bolt insert 312 comprises a bolt body 321 fabricated of carbon steel in a conventional manner. The body 321 includes a hex-shaped section 324 at one end and an externally threaded base 327 at the opposite end. The insert 312 is coated in a manner previously discussion.

Between the hex-section 324 and the threaded base 327, a circular cylindrical section 331 and a frusto-conical section 333 are formed. The circular cylindrical section 331 has a coated cylindrical outer surface 335. The OD of surface 335 is 0.895 inches. The surface 335 has an axial length of 0.165 inches.

The frusto-conical section 333 is adapted to seat in a wheel rim aperture (not shown) to fasten the wheel rim to a vehicle wheel. The threaded base 327 of the insert 312 threads into the wheel hub in a well known manner.

The cap 314, again formed from stainless steel sheet, comprises three axially aligned segments, a dome shaped end wall segment 351, a hex-shaped side wall segment 353 and a cylindrical side wall segment 355. The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment 353 are such that it slips easily over the coated hex-shaped section 324 in the insert body 321.

The ID of the cylindrical wall segment 355 is 0.875 inches. When the cap 314 is pressed onto the insert 312, the cylindrical wall segment 355 undergoes the aforedescribed plastic and elastic deformation as it is forced over the coated surface 335 on the bolt body 321. The resulting interference fit is again approximately 0.0025 inches.

Referring now to FIGS. 14 and 15, of a decorative capped wheel bolt assembly comprising a fifth embodiment of the invention is seen generally at 410. The assembly 410 also includes a bolt insert 413 and a decorative cap 414.

The bolt insert 412 comprises a bolt body 421 fabricated of carbon steel in a conventional manner. The body 421 includes a hex-shaped section 424 near one end and an externally threaded base 427 at the opposite end. The insert 412 is coated in a manner previously discussed.

Axially outside the hex-section 424, the insert 412 includes a circular cylindrical section 431. The circular cylindrical section 431 has a coated cylindrical outer surface 435. The OD of surface 435 is 0.615 inches. The surface 435 has an axial length of 0.150 inches.

The insert 412 also has a spherical section 433 adapted to seat in a conventional manner in a wheel rim aperture (not shown) to fasten the wheel rim to a vehicle wheel. The threaded base 427 of the insert 412 threads into the wheel in a well known manner.

The cap 414, again formed from stainless steel sheet, comprises three axially aligned segments; a dome shaped end wall segment 451, a cylindrical side wall segment 455, a hex-shaped side wall segment 453 and a flared lip 456. The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment 453 are such that it slips easily over the coated hex-shaped section 424 in the insert body 421.

The ID of the cylindrical wall segment 455 is 0.595 inches. When the insert 412 is pressed into the cap 414, the cylindrical wall segment 455 undergoes the aforedescribed elastic deformation. As it is forced over the coated cylindrical surface 435 on the bolt body 421, an interference fit of approximately 0.0025 inches is effected around the coated surface 435.

FIGS. 16 and 17 illustrate yet a sixth embodiment of a capped wheel assembly embodying features of the invention at 510. The assembly 510 includes a nut insert 512 and a decorative cap 514.

The nut insert 512 comprises a body 521 having a cylindrical bore 523 extending axially through it from a hex-shaped section 524 on one end to a frusto-conical base 525 on the other. The base 525 is adapted to seat in a wheel rim aperture (not shown). The bore 523 is internally threaded at 527. Like the inserts 12 and 112, the insert 512 is coated.

Between the hex-shaped head 524 and the frusto-conical base 525, the insert body 521 has a body section 533. The body section 533 of the illustrated insert body 521 has a coated cylindrical outer surface 535 with an OD on 1.160 inches and an axial length of 0.130 inches. Below the cylindrical body section surface 535, and above the frusto-conical base 525, there is an undercut 534.

The cap 514 comprises three axially aligned wall segments; a dome-shaped end wall segment 551, a hex cross—section side wall segment 553, a circular cylindrical side wall segment 555 and a crimp section 556. The configuration and internal cross-sectional dimensions of the hex-shaped side wall segment 553 are such that it slips easily over the coated, hex-shaped section 524 of the insert body (before the inward crimp section 556 is formed). The internal cross-sectional dimension of the circular cylindrical side wall segment 555 is such that a predetermined interference fit is formed between the inner surface 557 of the wall segment 555 and the coated cylindrical outer surface 535 of the insert body 521 when the cap 514 is press fit onto the insert 512.

The cap 514 is fabricated of stainless steel sheet with a nominal thickness of 0.018 to 0.020 inches. The inside diameter (ID) of the cylindrical wall segment 555 is preferably 1.140 inches. The cap 514 is pressed onto the insert 512 and the cylindrical wall segment 555 undergoes plastic and elastic deformation. The resulting interference fit is approximately 0.0025.

In this embodiment of the invention, the crimp section 556 is formed inwardly after the insert 512 is press fit into the cap 514 in the aforedescribed manner. Crimping may be accomplished as a continuation of the press-fit operation. The crimp section 556 is crimped into engagement with the undercut 534 on the insert body 521. The crimp feature is offered as an option where the assembly 510 may be subject to extreme wrenching abuse, and assures that it will remain intact under such conditions. It also provides a pleasing decorative appearance to the assembly. The interference fit and the crimp then both serve to hold the cap 514 securely on the insert 512 with the interference fit serving the further function of blocking the entry of moisture at the juncture of surfaces 535 and 537.

It should be pointed out at this point that the various inserts described might be plated first, and then coated. They might also be plated in a conventional manner and not coated. The invention contemplates employing any of these approaches to protecting a carbon steel insert from the elements. It should also be understood that although only the third embodiment assembly 210 (FIGS. 10 and 11) illustrates using separate interference fits at two axially spaced, mating cylindrical surfaces, the invention contemplates the use of either one or two sets of mating cylindrical surfaces in any embodiment as a matter of choice.

While preferred embodiments of the invention have been described, it should also be understood that the invention is not so limited and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein. 

1. A decorative cap and a wheel fastener for a vehicle wheel, comprising: a) a fastener insert body having threads formed thereon encircling the axis of said body; b) said body including one section having an external surface with a polygonal cross-section encircling said axis; c) said body including another section having an external surface with a circular cylindrical cross-section encircling said axis; and d) a cap including one wall segment having an internal surface with a polygonal cross-section; e) said cap including another wall segment having an internal surface with a circular cylindrical cross-section; f) said cap being formed of sheet metal which is deformable both plastically and elastically; g) said circular cylindrical cross-section internal surface of said cap having a predetermined inside diameter; h) said circular cylindrical cross-section external surface of said insert body having a predetermined outside diameter; i) said predetermined inside diameter being sufficiently less than said predetermined outside diameter whereby said other wall segment of said cap is adapted to fit onto said insert such that said other wall segment is plastically and elastically deformed with said elastic deformation forming at least a 0.002 inches interference fit around the interfering cylindrical surfaces to provide a tensile hoop stress to hold the cap on the body.
 2. The cap and fastener of claim 1 further characterized in that: a) said external surfaces of said insert body are coated with an anti-oxidant material; and b) said anti-oxidant material coating is approximately 0.001 inches thick.
 3. The cap and fastener of claim 1 further characterized in that: a) said external and internal circular cylindrical cross-section surfaces are free of adhesive material.
 4. The decorative cap and wheel fastener of claim 1 further characterized in that: a) said cap is formed of stainless steel sheet.
 5. The cap and fastener of claim 1 further characterized in that: a) said elastic deformation of said other wall segment is adapted to form between 0.002 and 0.006 inches interference fit around the interfering cylindrical surfaces.
 6. The cap and fastener of claim 1 further characterized in that: a) said internal polygonal surface is adapted to be seated over said external polygonal surface on said insert in a non-interference fit relationship.
 7. A method of assembling a decorative cap and wheel fastener for a vehicle wheel, comprising the steps of: a) providing a wheel fastener including an insert body having threads formed thereon encircling the axis of said body; b) forming an external surface with a polygonal cross-section encircling said axis on one section of said body; c) forming an external surface with a circular, cylindrical cross-section of predetermined diameter encircling said axis on another section of said body; d) forming a decorative cap for said wheel fastener from sheet metal which is plastically and elastically deformable, said cap being formed with one wall segment having an internal surface with polygonal cross-section and another wall segment having an internal surface with a circular cylindrical cross-section, the circular cylindrical internal surface having an inside diameter which is sufficiently smaller than the predetermined diameter of said external surface so that when the cap and insert are press fit together, said cap elastically deforms at least 0.002 inches around the interfering cylinderial surfaces to provide a tensile hoop force sufficient to hold the cap securely on the body; and e) press fitting said insert and said cap together so that said other wall segment of said cap encircles said other section of said insert body in an interference fit and said one wall segment of said cap encircles said one section of said insert body.
 8. The method of claim 7 further characterized by and including the step of: a) forming said decorative cap from stainless steel sheet material having a nominal thickness about 0.018 inches to 0.020 inches.
 9. The method of claim 7 further characterized by and including the step of: coating at least one of said circular cylindrical external and internal surfaces with an anti-oxidant material which is chromium free.
 10. The method of claim 7 further characterized by and including the step of: a) press fitting said insert and cap together without an adhesive between said circular cylindrical surfaces.
 11. The method of claim 7 further characterized in that: a) when said insert and cap are press fit together, said one wall segment of said cap encircles said one section of said insert body in a non-interference relationship. 